Shock-wave devices are commonly used clinically for therapeutic treatment. For example, an electrohydraulic shock-wave lithotripter is a device that generates a focused shock-wave and directs it onto a clinical target, such as a kidney stone. An electrohydraulic shock-wave lithotripter is only one example of the shock-wave devices that can benefit from the present invention. This device is characterized by a focusing reflector having spaced-apart first and second foci. A shock-wave generator is positioned substantially at the first foci and is adapted to discharge shock-wave creating energy outwardly from itself to the focusing reflector. The focusing reflector is configured to receive shock-wave energy and focus it and direct it as a focused wave to a target (e.g. kidney stone) at the second foci.
One use of a shock-wave focusing device is to fragment kidney stones into small pieces that can then be safely removed from a patient via the urinary tract. There is evidence that normal tissue can at the same time be damaged.
Several thousand shock-wave generations are necessary to fragment a kidney stone. The clinician takes care to operate the lithotripter at the highest safe rate of operation. Currently, the instrument is operated typically at 0.5–2.0 Hz pulse repetition frequency (PRF). There is a need to decrease the total number of shock-waves that are delivered to the kidney stone to cause its comminution, in order to reduce the unwanted and unhealthy bioeffects on healthy tissue.
A principal object of the present invention is to increase the efficiency of a focused shock-wave device so that it can perform its function satisfactorily by use of a reduced number of focused shock-waves or by an increased PRF.